The present invention relates generally to head moving mechanisms (or head actuators) for a recordable medium, and more particularly to a head arm that supports and moves the head. The recordable medium typically is a disk in form, but broadly covers various types taking the form of a card, a sheet and others. The head may move in any direction, straight, swingingly, up and down, etc. The head arm as one exemplified embodiment of the present invention is suitable for those disk units which broadly include a magnetic disk unit, optical disk unit, magneto-optic disk unit, DVD unit, CD audio player, a variety of game machines using a dedicated disk.
There has been a demand for quick head positioning onto a specified track in magnetic or other disk units. The head moving mechanism typically includes a head, a head arm, and a suspension that connects the head and arm. Reduced moment of inertia of the head moving mechanism is effective for the quick head positioning. A pierced head arm has been thus proposed to reduce the weight of the head arm.
As shown in FIG. 32, for example, a conventional head moving mechanism 10 includes a head arm 20, a suspension 30, and a head 40. Hereupon, FIG. 32 is an illustrative schematic plan view of the conventional head moving mechanism 10. The head arm 20 is connected to the suspension 30 at its top 22 and to a rotation shaft 50 at its base 24. The head arm 20 also includes a through hole 26 that perforates from its top surface through its bottom surface for weight reduction. One or two through holes 26 are made as large as possible to the extent that the head arm 20 may maintain specified rigidity. The head arm 20 crosses a disk at its upper side of the dotted line in FIG. 32.
However, the conventional disk unit has a disadvantage in that it cannot quickly position the head at a target position due to disturbance (vibration, etc.) by airflow between disks. The airflow is produced by rotations of the disks as indicated by a solid arrow A in FIG. 32, and has a deleterious effect especially in a hermetic space. In particular, where a head arm is located between the disks and support a pair of heads that read data on the upper and lower disks would narrow the hermetic space, and thus increase the effect of the airflow.
As shown by an arrow in FIG. 33, the airflow is sucked into the hole of the head arm, swirls, and causes vibration at frequencies commensurate with the current. Hereupon, FIG. 33 is a sectional view taken along a line Bxe2x80x94B of the head moving mechanism 10 shown in FIG. 32 when placed between a pair of upper and lower disks 2. A magnetic disk unit in the past rotated the disks at a relatively low rotary speed, i.e., a few thousand rpm, and the air flew at low velocity. Therefore the disturbance by the air had little effect, and no consideration has been given to a shape of the head arm in view of the airflow.
However, the trend toward accelerated disk speed in recent years has brought about increased disk rotating speed, which has boosted the velocity of the airflow around the head arm. Consequently, recent years have seen a nonnegligible effect of the disturbance by airflow on the disk unit. Specifically, an arm has a sectionally rectangular shape and includes a part that orthogonally crosses the airflow, thus suffering for the high air drag. In addition, the airflow greatly deflects out of top and bottom ends of surfaces orthogonal to the airflow, and vibrates the arm. Moreover, the disturbed airflow in the presence of the arm disadvantageously affects the disks and induces vibrations of the disks. As the velocity of the air increases, the disturbance by the air pressure has induced high-frequency disturbance extending up to a few kHz in addition to low-frequency disturbance. Since the according density of the disk increases year after year, it is necessary not only to improve a control performance of the head arm but also to reduce the disturbance by airflow, in order to improve a positioning performance.
Therefore, it is an exemplified general object of the present invention to provide a novel and useful head arm, head moving mechanism, disk unit, and method of manufacturing the head arm, in which the above disadvantages are eliminated.
Another exemplified and more specific object of the present invention is to provide a head arm, head moving mechanism, disk unit, and method of manufacturing the head arm that permits quick positioning of the head.
In order to achieve the above objects, the head arm as one exemplified embodiment of the present invention comprises a main body, partially located above a recordable medium, that the main body includes a first surface opposite to the recordable medium and a second surface opposite to the first surface, the first and second surfaces having no perforation above the recordable medium as viewed from the recordable medium, a first connector portion connected to the main body, and connectible to a driving portion, and a second connector portion connected to the main body, and connectible to a head. This head arm allows no airflow to pass through the head arm, and thus undergoes little influence of disturbance such as vibration or the like.
The head arm as another exemplified embodiment of the present invention comprises a main body, partially located with a first area above a recordable medium, that the main body includes a first surface opposite to the recordable medium and a second surface opposite to the first surface, the first and second surfaces having a through hole, a first connector portion connected to the main body and connectible to a driving portion, and a second connector portion connected to the main body, and connectible to a head, wherein the through hole is formed on only one side with respect to a line that halves the first area. This head arm becomes lightweight because of the through hole, and also reduces disturbance by airflow, by the restricted position of the through hole. Particularly, the head arm having a plurality of through holes may effectively prevent the disturbance.
The head arm as still another exemplified embodiment of the present invention comprises a main body, partially located above a recordable medium, that the main body includes a first surface opposite to the recordable medium and a second surface opposite to the first surface, the first and second surfaces having a plurality of through holes formed like a mesh, a first connector portion connected to the main body, and connectible to a driving portion, and a second connector portion connected to the main body, and connectible to a head. This head arm having meshed through holes would reduce the magnitude of the airflow as passing through them.
The head arm as still another exemplified embodiment of the present invention comprises a main body, partially located above a recordable medium, wherein the main body includes a buffer mechanism, connected to at least one of a third surface opposite to an airflow generated above the recordable medium and a fourth surface opposite to the third surface for mitigating disturbance of the airflow, a first connector portion connected to the main body, and connectible to a driving portion, and a second connector portion connected to the main body, and connectible to a head. This head arm uses the buffer mechanism (e.g., a step, chamfered portion, projection portion formed on at least one of the third and fourth surfaces, and/or through hole that perforates the third and fourth surfaces) to restrict disturbance by the airflow.
The head moving mechanism as one exemplified embodiment of the present invention comprises any one of the above head arms, and a head connected to the second connector portion of the head arm. This head moving mechanism may achieve the same operation as the above-described head arms.
The disk unit as one exemplified embodiment of the present invention comprises any one of the above head arms, wherein the recordable medium is a disk, a head connected to the second connector portion of the head arm, a driving portion connected to the first connector portion of the head arm, a signal processor portion that handles a signal communicated between the head and the disk, a rotor portion that rotates the disk, and a controller portion that controls movements of the head, operations of the signal processor portion and rotor portion. This disk unit may achieve the same operation as the above-described head arms.
The method of manufacturing a head arm comprises the steps of forming a body base material having a desired thickness, providing a through hole for making the body base material lightweight, and sealing at least a part of the through hole. This manufacturing method of a head arm makes it possible to provide a lightweight head arm while preventing disturbance by airflow.
Other objects and further features of the present invention will become readily apparent from the following description of the embodiments with reference to accompanying drawings.